An assessment of methods for the digital enhancement of rock paintings: the rock art from the precordillera of Arica (Chile) as a case study
Authors:
Cerrillo-Cuenca et al
Abstract:
The digital tracing of rock art is becoming a standard for archaeologists working in this field of research. The lack of specific software for this task has resulted in archaeologists either using solutions that are not statistically robust enough or working with overly generic fields of image analysis. This paper will assess the application of three techniques for digital tracing: Principal Components Analysis, K-means, and Decorrelation Stretch. In addition to these techniques of image analysis, this paper will also explore three selective techniques that classify or enhance pigmentation. These analyses have been implemented in a software package called PyDRA (developed by one of the authors, ECC). This software makes use of several scientific libraries for the digital analysis of an image.
As a case study, we chose three rock art sites located between 3100 and 3500 m above sea level in the precordillera of Arica, the northern region of Chile. All of the paintings are located inside rock shelters that are easily accessible; however, we lack a systematic recording for analysing these sites. Pampa El Muerto 14 and Mullipungo 1 were recorded through direct tracings between 1980 and 1990. The Lupica 1 site was identified only in 2013 and has not been recorded until now. Due to the advancement of technology in the years since the 1980s, we have been able to compare the proficiency of different digital and statistical techniques. Our study uses the most adequate parameters and enables us to trace the paintings digitally without actually handling the surface of the rock.
A rock engraving made by Neanderthals in Gibraltar
Authors:
Rodríguez-Vidal et al
Abstract:
The production of purposely made painted or engraved designs on cave walls—a means of recording and transmitting symbolic codes in a durable manner—is recognized as a major cognitive step in human evolution. Considered exclusive to modern humans, this behavior has been used to argue in favor of significant cognitive differences between our direct ancestors and contemporary archaic hominins, including the Neanderthals. Here we present the first known example of an abstract pattern engraved by Neanderthals, from Gorham’s Cave in Gibraltar. It consists of a deeply impressed cross-hatching carved into the bedrock of the cave that has remained covered by an undisturbed archaeological level containing Mousterian artifacts made by Neanderthals and is older than 39 cal kyr BP. Geochemical analysis of the epigenetic coating over the engravings and experimental replication show that the engraving was made before accumulation of the archaeological layers, and that most of the lines composing the design were made by repeatedly and carefully passing a pointed lithic tool into the grooves, excluding the possibility of an unintentional or utilitarian origin (e.g., food or fur processing). This discovery demonstrates the capacity of the Neanderthals for abstract thought and expression through the use of geometric forms.
Recently discovered rock art on the walls of a cave in the Egyptian Western Desert has been provisionally dated by a Cambridge University archaeologist as between 6,000 and 7,000 years old, created at least 1,000 years before the building of the pyramids. The drawings add weight to the argument that Egyptian culture drew on cultural influences from Africa and not only from the Near East.
Spotted by a tourist to Wadi el Obeiyid, north of Farafra Oasis, drawings of a giraffe, a bovid (cow-like mammal) and two boats, plus the outline of a human hand, were examined last month by Dr Giulio Lucarini who co-leads a team of archaeologists looking at the pathways, and timings, by which domestic animals and plants from the Levant arrived in Egypt. The engravings are thought to have been discovered in 2010. The onset of revolution in Egypt meant that they were not investigated for some time.
